Rust inhibitor formulation



RUST INHIBITOR FORMUIJATION Charles F. Gebelein, Fanwood, Harry W.Rude], Rosellqand Marion Gargisa, Elizabeth, N J a'ssignors toEsso'Researclr' and Engineering" Company, a corporation of Delaware NoDrawing. Application Mayzzs, v1953 Serial No. 358,178

4 Claims. (Cl; 44-7 5) Thepresenrinventien is concerned" with a methodand compositiomfo'r' inhibiting, the rusting. characteristics ofpetroleum'distillates. The' rust inhibitorsutiliz'ed in thepresent'invention" are directly dissolved in the petroleum distillatesoas '"to' substantially completely eliminate any rusting of ferroussurfaces'in the presence of the distillate'product. 'The'additivesutilized'are related broadly tdthose' disclosed in'a plic'ation,Serial'No. 325,694, tiledDecernber 12, 1952,:and nowU. S. 2,791,495;-for HarrywaRudeliandfMarion Gargisa, entitled Rust Inhibited DistillateProducts. The additives covered in the present application constitute amixture of an ammonium salt of an alkylated behzen'esulr'onate with anammonium salt'of alkyl'phosphoric acid. When utilizing these twoclassesof compoundsin conjunction with one another; an unexpectedvery.desirable synergistic effect is secured with respect to their rustpreventive qualities;

One problem which exists in the handling and use of petroleum products.is the rusting which frequently occurs in storage containers such aspipelines, storage tanks, engines, etc.. In order to reduce and overcomethe problems, many solutions have been suggested. As amatter of fact, agreat amount of technical consideration is now being given to thediscovery of effective rust inhibitors for petroleum products. Therusting problem which occurs in storing and using petroleum productsoccurs usually as the result of'traces of moisture which are inevitablypresent in petroleum distillates. Moisture finds its way into thedistillates in a variety. of ways.

wane water is not appreciably soluble in petroleum distillatestraces ofmoisture are, in fact," dissolved in heating oil,. gasoline, kerosene,etc. Again,.it is impossible-to prevent entrainment of moisture in-suchproducts during storage and handling. In this connection, .forexample,.storage tanks are generally provided with breather devices topermit the intake and exhaust of air during atmospheric temperaturechanges. As a result;cool,,moisture-laden air is generally drawn into astorage tank at'night, resulting in the condensation of moisture in thetank. A portion of this moisture is dissolvedinor entrained inpetroleumproducts when pumped from the storage tanks.

There havebeen a number of suggestions for overcoming the corrosion dueto moisture carried by oil products. For. example, anumber ofwater-soluble rust inhibitors are known and have been employed. Use ofwater-soluble inhibitorsisdisadvantageous for several reasons,- however-Theinhibitor is largely lost when water is separated fromoil productsduring handling so that the desired'rust inhibition for remainingresidual traces ofwatet may'be lost. AddltlOlT of water-solubleinhibitors to oil again necessarily requires=addition-of water to theoil which aggravates the problem intended to be solved. It is thereforea particular object of this invention to provide a rust inhibitor whichis soluble in the oil product to be inhibited.

It may be observed that attempts have been made in 2. the' past toprovide suitable oil-soluble rust inhibitors. The problem ofv providingsuch an inhibitor is complicated by a number of factorshowever. It isclearly necessary that the-inhibitor-should not degrade the oil product,and thus, should-not decrease-the octane number of a gasoline forexample, and-should not otherwise afiect critical inspections offthe oilproducts. In this connection a particular problem encountered withgasoline rust inhibitors is the tendency ofm'anyinhibitors to discolordyed gasoline- A more specific object of this invention therefore isto'provide an oil-soluble rust inhibitor which will suitably inhibit'theoilproduct against rusting, while in no way affecting the criticalinspections or characteristics of the oil product.

Theseobjectives are' satisfied in accordance with this invention by. atwo-component rust inhibiting composh tion. Themake-up of thiscompositionis based on the discovery that two particular'classes ofrustinhibitors are beneficially employed in cornbinationto obtain rustinhibiting characteristics unobtainable by use of single componentsselected from eitherclass of inhibitors. in other words, the inventionis'ba'sedon thediscovery of a synergistic action between two classes ofrust inhibitors. In this combination one inhibitor constitutes anarmmonium salt of-an alkylated benzene sulfonate.

The ammonium salt or'soap is preferably a sulfonate ofbenzene which hasbeen alkylated with a poly-propylene. The poly-propylene preferablycontains from about 9 to 15 carbon atoms in 'the'molecule. Thesepolymers, as for example thetetra-propylene polymer, may be secured byany satisfactory polymerization operation. One satisfactorymethod ofpolymerizing light hydrocarbons, such as propylene and the like, is toutilize the socalled U. 0. P. process. In'essence, this'operationcomprises passing light hydrocarbon gas containing propylene in contactwith the polymerization-catalyst such as phosphoric acid impregnated onkieselguhr, silica gel, and the like. Temperatures are in the-ra'ngeofabout 300 F. to 500 F., preferably about 450 F. The pressures may varyin the range from about 200 to 5,000 lbs/sq. in. gauge.

The alkylated'benzene is prepared by alkylating benzene with apolymerized light hydrocarbon such as, for example, with tetra-propylenepolymer prepared as described above. In a typical preparation, 5 molesof tetra-propylene are added portion-wise to an agitated mixture ofonemole of benzene, 0.2 mole of anhydrous aluminum chloride, and 0.05mole of chloroform. The reaction temperature is maintained preferablybelow about 50 C. Afterthe addition, which requires about 0.5 hour,the'reaction' mixture-is stirred for about an additional 0.5 hour. Theproduct is washed with water, dried and distillal. The distillation isfirst carried out at atmospheric pressure to remove the unreactedbenzene and tetra-propylene. The distillation is then carried out underreduced pressure'to collect the mono-alkylated benzene. The bottomsboiling above 320 C. at 760 millimeters are'employed in the sulfonationstep.

In the sulfonation step the alkylated benzene, prepared as describedabove, is treated portion-wise with rapid agitation with '50 volumepercent of 20% oleum maintained in the reaction temperature below about50 C. during the addition. After the addition of theoleum, the insolubleacid sludge-is allowed to-settle out and the sulfonated product decantedoff.-

The ammonium 'salt'of-the sulfonated product is formed by bubblingingaseous ammonia until absorption is complete.

The second constituent of the rust inhibiting composition of the presentinvention is an ammonium salt of alkyl phosphoric acid. The preferredsalt is an ammonium salt of C oxo phosphoric acid. As used herein, theterms alkyl and aliphatic include cyclo-alkyl,

and cycle-aliphatic. These acids are preferably prepared by the reactionof P with an alcohol. The preferred alcohols to be reacted are themonohydric primary alcohols having 6 to 18 carbon atoms. While aliphaticalcohols of this character are preferred, aryl alcohols may also beemployed. The reaction between P 0 and the alcohol results in theformation of what may be called esters or acid-esters of phosphoricacid. Depending upon the reactant proportions and the reactionconditions, mono-, di-, or tri-alkyl phosphoric acids may be obtained.Practically the reaction product constitutes a mixture of these esters.For this reason this constituent of the rust inhibiting composition isbest defined as the ammonium salt of the reaction product of P 0 and analcohol.

The two-component rust inhibiting composition may also be prepared bymixing the alkylated benzene sulfonic acid with an alkyl phosphoric acidand forming a mixed salt of these acids. As examples of this procedure,ammonia may be reacted with the mixed acids to form mixed ammonium soapsof the sulfonic acid and alkyl phosphoric acid.

In order to obtain the desired synergism between the ammonium salt ofhydrocarbon sulfonic acid and the ammonium alkyl phosphoric acid salt,these constituents should be combined in proportion ranging from about ito l, to 1 to 3 respectively by weight.

The combined rust inhibiting additives, in the ratios indicated, may beemployed economically in petroleum products in the concentration ofabout pound per 1,000 barrels up to pounds or more per 1,000 barrels. Inthis range of concentrations it is generally suitable and preferred touse a concentration of about 1 to 5 pounds of combined rust inhibitorsper 1,000 barrels of product. Of course, in special circumstances wherethe primary function of the oil composition may be that of rustprevention, it is practicable and desirable to use higher concentrationsof the combined rust inhibiting additives up to the limit of theirsolubility in oil. The oil products which may be successfully inhibitedin this way may be defined as the distillate petroleum products. Thus,the oil product may constitute gasoline, kerosene, lubricating oil,heating oil, gas oil, etc.

in order to demonstrate the utility and benefits of this invention, thefollowing examples are presented. In these a rusting test was employedwhich generally corresponds to A. S. T. M. test method D665. This testwas modified however, by lowering the temperature to 77 F. The testrequired stirring of a mixture of 300 cc. of oil product with cc. ofdistilled water at 77 F. with a cylindrical steel rod immersed therein.At the end of 24 hours the rod was examined and rated in accordance withthe amount of rust which had formed.

in a series of tests which were conducted, the ammonium salt of analkylated benzene sulfonic acid prepared as described above was employedas the first con stituent of the rust inhibiting composition. The secondconstituent constituted the ammonium soap of di-alkyl phosphoric acidformed by the reaction of one mole of phosphoric pentoxide and fourmoles of iso-octyl alcohol synthesized by the OX0 process. The olefinfeed to the OX0 process was a C copolymer of propylene and nbutylene. Toobtain the alkyl phosphoric acid, 66 g. of phosphorus pentoxide wasadded portionwise with stirring to 260 g. of iso-octyl alcohol at about60 C., following which stirring was continued for 2 hours at 60 C. Thereaction product was heated to 140 C. and blown with nitrogen underreduced pressure for 4 hours to expel unreacted alcohol and water formedduring the reaction. To prevent darkening the productduring the TABLEModified A. S. T. M. rust tests [Blends in 100/130 aviation gasoline]inhibitor (3 pounds/ 1000 bbls.): Rust test rating Ammonium alkylbenzene sulfonate R-S Ammonium C Oxo phosphate R-4 ammon. alkyl benzenesulfonate, 50%

ammon. C OX0 phosphate R-l 33 /s% ammon. alkyl benzene sulfonate,

66% ammon. C OX0 phosphate R-l 25% ammon. alkyl benzene sulfonate, 75%

ammon. C OX0 phosphate R-1 None R-7 Test procedure involves amodification of ASTM Method D-665 in which a mixture of 300 cc, ofproduct and 30 cc. of distilled water are stirred in contact with apolished steel rod for 24 hours at 77 F. The extent of rusting is ratedas follows:

R1-free of rust R-2-trace rust R3-less than 5% of surface rusted R-4-5to 50% of surface rusted R-55099% surface rusted R-G-surface coveredwith light rust R7surface covered with rust From the above, it isapparent that a synergistic rust preventive effect is secured by the usein combination of the compounds covered by the present application.While the antirusting effect is secured with respect to any petroleumdistillate such as gasoline, kerosenes, heating oils and the like, it isparticularly effective when used in conjunction with motor fuels andheating oils.

What is claimed is:

1. A petroleum distillate fuel having incorporated therein as a rustinhibiting additive in a concentration of about A to 25 pounds per 1000barrels of distillate a mixture of one part by weight of an ammoniumpolypropyl benzene sulfonate wherein the polypropyl group contains from9 to 15 carbon atoms and from one to three parts by weight of anammonium isooctyl phosphate.

2. A fuel as defined by claim 1 wherein said am"- monium isooctylphosphate is ammonium di-isooctyl phosphate.

3. A fuel as defined in claim 2 in which the polypropyl group is atetra-propylene polymer.

4. A fuel as defined in claim 3 in which the amount of mixture employedis about 1 pound to 5 pounds per thousand barrels of distillate.

References Cited in the file of this patent UNITED STATES PATENTS OTHERREFERENCES Industrial and Engineering Chemistry, May 1948, pages890-897.

1. A PETROLEUM DISTILLATE FUEL HAVING INCORPORATED THEREIN AS A RUSTINHIBITING ADDITIVE IN A CONCENTRATION OF ABOUT 1/4 TO 25 POUNDS PER1000 BARRELS OF DISTILLATE A MIXTURE OF ONE PART BY WEIGHT OF ANAMMONIUM POLYPROPYL BENZENE SULFONATE WHEREIN THE POLYPROPYL GROUPCONTAINS FROM 9 TO 15 CARBON ATOMS AND FROM ONE TO THREE PARTS BY WEIGHTOF AN AMMONIUM ISOOCTYL PHOSPHATE.